Main Data Conversion: Rasterization and Vectorization (Especially for GATE-Geospatial 2022)

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There are main two types of data conversion:

This Diagram Shows Two Types of Data Conversion

Rasterization refers to converting vectors into rasters. While vectorization transforms rasters in vectors.

We know the two main data models and graphics are vector and raster data.

  • Conversion of vector to raster data is called rasterization
  • Conversion of raster to vector data is called vectorization

Rasterization: Convert Vector to Raster

Graphic editing software, it expects your rasters and vectors to have a geographic coordinate system. But really it has similar functionality to Adobe Photoshop or GIMP that you can perform for rasterization and vectorization. For example, a simple vector line with a vertex at the start and end points,

This Image Shows a Vector Line with a Vertex

Use the Rasterize (Vector to Raster) Tool: The horizontal and vertical parameters will determine the output pixel size. After setting all the parameters, click RUN for rasterization.

This Image Shows Rasterized Line

Finally, the output will look like a gridded version of your vector.

Vectorization: Convert Raster to Vector

Takes a discrete raster and convert it to vector. When we have a raster data set like our buildings layer, it is a matter of adding it to QGIS. Here is what the raster buildings look like in the table of contents:

Image Shows a Raster Data Set like Our Building

In this case, the vectorization tool in GRASS is looking for.

This Image Shows Vectorized Buildings

As a reminder, vectorization creates all the necessary vertices and paths as shown with the building outlines. Concisely, this tool digitizes the raster for you converting it to a vector.

Other Considerations

While vector data structure provides a simpler and more abstract data representation than raster image, an automatic conversion from raster to vector, so it called vectorization process, is not a very easy task, although the opposite direction (from vector to raster) is quite trivial and straight forward.

A complete raster to vector conversion process includes image achievement, pre-processing, line tracing, shape recognition, topology creation and attribute assignment.

You can latitude-longitude vector data to a grid at any resolution you choose to make a raster base map or grid layer. But you can also perform vector-to-raster conversions from the command line. The principal function for gridding vector data is vec2mtx, which allocates lines to a grid of any size you indicate, marking the lines with 1s and the unoccupied grid cells with 0s. The grid contains doubles, but if you want a logical grid

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